Where does the burden lie most heavily?
On those sinned against who are loathe to forgive or those who sin and expect to be forgiven?
I know what I think. What do YOU think?
Should everyone be able to forgive? Yes.
Are all things forgivable? Yes.
Are all people willing to forgive? No.
Are all people willing to forgive all things? No.
Are some offences extremely hard to forgive? Most definitely!
Do all people have to accept forgiveness (if offered)? No.
The "burden" (as you put it) lies heavily on the one whose conscience is bothering them.
Now, I know what you're going to say... things like rape, murder, child abuse (etc.) are unforgivable. So before I go any further, let me just say that forgiveness does NOT mean absolution. Forgiveness is NOT glossing over or denying the seriousness of an offense. Forgiveness does NOT mean forgetting, condoning or excusing offenses. What happened, happened and it can never be erased. Forgiveness, though, is simply a deliberate decision by a person to release feelings of resentment or vengeance toward a person or group who has harmed them, regardless of whether they actually deserve that forgiveness.
It's one thing to say "I could never forgive {insert offence(s) of choice here}. It’s another to live through the offence(s). Anger at something is never as strong as the anger when that something happens to you. Anger is like an acid. It burns and eats away at a person holding it, until eventually it’s all that left. Forgiveness, on the other hand, brings the forgiver peace of mind and frees them from that corrosive anger.
So again, in MY opinion…
Should everyone be ABLE to forgive? Yes. But that doesn’t mean all people will.
Are all things forgivable? Yes. But again, as of now, not all things have happened to me.
Do all people have to ACCEPT forgiveness (if offered)? No. They can hold onto the anger, bitterness, resentment, and hatred as long as they choose.
Often the offender refuses forgiveness, as either they don't recognize an offence, or they don’t believe the offence was their fault.
Reciprocation isn't always a necessity. Some people have forgave a person who died many years earlier (definitely no reciprocation gonna happen there).
Forgiveness does NOT mean one has to forget the offence. Nor does it mean one is sanctioning the offence. It simply means you no longer hold the offense against them. Your citing of Jesus is an excellent example. Here you have an innocent man - the Son of God Himself, no less - being treated as if he were a common criminal. He’s cruelly nailed to a cross (a torturous form of execution), soldiers gamble for his clothes, and crowds of people mock and laugh at him. Those people sure didn't want forgiveness. As far as they were concerned, they were doing anything wrong. Now, God, on the other hand, had every right to, as we might say, “vaporize every last one of them” for what they were doing to His son. Jesus asked Him to forgive them instead. God didn’t forget that offence (as if it never occurred), rather He forgave it. Jesus was in essence saying, Father, don’t hold this against them, because they really don’t understand what they’re actually doing.
Forgiveness is NOT easy! Sometimes we just want to put the incident out of our head. What’s done is done; move on; don’t look back. That’s perfectly fine. However, sometimes our mind doesn’t fully leave it behind. Sometimes it keeps a little root connected to the incident. It may be inconsequential, or it may start to bug us, days, months, maybe even years later. Sometimes forgiveness is a way to ease that troubled mind.